The present invention relates to the manufacture of reinforcing preforms for structural composites, and more particularly to improving and optimizing the manufacturing process, including reducing friction in the material supply system and manufacturing preforms of various thicknesses.
The present invention relates to methods and systems for making rigid three-dimensional reinforcement preforms used in resin transfer molding (RTM) and structural reaction injection molding (SRIM) processes for the manufacture of structural composites. The manufacture and use of structural composite materials is becoming increasingly important today, particularly in components for the automotive industry. Structural composites are lighter in weight than conventional steel or metal components and can result in additional advantages, such as allowing fully automated, highly controllable processes, better part-to-part consistency, reduced waste or scrap, and equivalent or increased component performance.
In general, the structural reinforcing preforms are made from a sprayed chopped material, such as glass and carbon fiber, which is held together by a binder and molded into a precise form and shape. The preform in turn is then molded into products, such as composite components (both structural and nonstructural) and used in automobiles or other vehicles.
The preform material is chopped and applied along with a powdered binder to a preform screen in a mold using a robotic routine. Positive air flow through the screen holds the chopped material on the screen surface. When the spraying is completed, the mold is closed and the preform is compressed to the desired thickness. Heated air is first drawn through the screen in order to melt the binder. Thereafter, cooled or ambient air is drawn through the preform setting the final shape. Once the preform is completed, it is demolded and transferred to a component mold where the structural component is molded.
Although present automated preform processes and systems have been used to produce satisfactory structural composite products, a need exists to improve the processes and systems, particularly to reduce the cost, increase the output and reliability, and make components of various configurations and thicknesses.
It is an object of the present invention to provide improved systems and processes for making rigid three-dimensional reinforcement preforms for resin transfer molding (RIM) and structural reaction injection molding (SRIM) processes for composite components and products. It is also an object of the present invention to reduce friction in the supply of the reinforcing materials to the application equipment and allow greater ease of processing of the string binder materials. It is another object of the present invention to provide eyelets to reduce friction in the supply of fiberglass roving materials to the application devices.
It is a still further object of the present invention to provide improved processes and systems for the manufacture of reinforcing preforms of various configurations and thicknesses.
In accordance with these objects, the present invention provides improvements and advantages over known preform processes and systems.
A series of eyelets are used in order to guide the string reinforcing materials from the doffs or bobbins to the chopper devices or applicators, particularly around the curved portions of the material path. This reduces friction and allows the chopping and application process to proceed more efficiently. Eyelets are held in place along a curved form and tubular members can be provided between the eyelets.
With the present invention, preforms can be provided of various configurations and thicknesses. This allows the tailor blanking of composite components.